1. What is black when you buy it, red when you use it, and gray when you throw it away ?

2. How can you throw a ball as hard as you can and have it come back to you even if it doesn't hit anything there is nothing attached to it and no one else catches or throws it ?

3. When deepak was six years old he hammered a nail into his favorite tree to mark his height. Five years later at age eleven , deepak returned to see how much higher the nail was. If the tree grew by ten inches each year, how much higher would the nail be?

4. A man is trapped on a frozen lake in an isolated region. The frozen surface is frictionless and no grip of any kind can be attained over it. He just has a mobile phone in his pocket but when he takes it out to call for help, he finds out that there is no reception.

There is no wind force that may help him in escaping. What will he do to escape the lake and save himself from freezing to death?

5. You are given two metal rods and then taken into a room. You are left there to identify which one of the metal rods you have is a magnet. Now you have no other metal object in the room with you. Also, the two rods are exactly similar to each other in looks.

What method will you use to determine which one of the rods is actually a magnet ?

1. An astronaut orbiting in a space capsule at normal atmospheric pressure ejects 100 grams of water into the vacuum of space. How much water will turn into ice?

2. At a party, everyone shook hands with everybody else. There were 66 handshakes. How many people were at the party?

3. All students in the physics class also study mathematics. Half of those who study literature also study mathematics. Half of the students in the mathematics class study physics. Thirty students study literature and twenty study physics. Nobody who studies literature studies physics. How many students in the mathematics class study neither physics nor literature?

4. From what height would a whale have to fall (assuming no air friction) to attain a speed of 42 mph?

5. A dropped ball loses half of its potential energy in the first two seconds of its drop. From what height was the ball dropped?

6. An elevator has a mass of 1,500 kg. A boy is riding in the elevator as it travels from the tenth floor to the twentieth floor. The height of each floor is 4 meters. If the potential energy of elevator and passenger increases by 606,424 J, what is the boy's mass?